Superposition Principle

The Superposition Principle postulates that the response of a system (or the result of an equation) to the sum of two inputs pondered by constants is the response the system would have to each of the inputs, pondered by the same constants and summed. In mathematical terms, we have:

$$\Phi_{t}(x_{0}+y_{0})=\Phi_{t}(x_{0})+\Phi_{t}(y_{0})\,$$